1. Field of the Invention
The present invention relates to a semiconductor device including a logic circuit.
2. Description of the Related Art
Techniques for fabricating transistors with the use of a semiconductor thin film formed over a substrate having an insulating surface have advanced in recent years, and such transistors are widely used in electronic devices such as integrated circuits (ICs) and image display devices (display devices).
As a semiconductor material that can be applied to transistors, silicon is widely known. As other materials, oxide semiconductors such as indium oxide and zinc oxide and III-V compound semiconductors such as gallium arsenide have attracted attention.
For example, Patent Document 1 discloses a transistor using an amorphous oxide semiconductor containing indium (In), gallium (Ga), and zinc (Zn).
Note that transistors formed using the above oxide semiconductor are n-channel transistors. As a result, logic circuits formed using the transistors are logic circuits in which all the transistors have the same conductivity type.